Geology Reference
In-Depth Information
Continuous surface-wave profile
1.0
Date: 01/12/05
Site: GE Healthcare, Amersham, Location 5
2.0
120
100
3.0
80
60
4.0
40
20
5.0
0
0
50
100
150
Frequency (Hz)
6.0
7.0
80
60
8.0
40
20
0
9.0
0
50
100
Frequency (Hz)
0
200
400
Shear modulus, G
(MPa)
max
Figure 14.3
Phase angle-frequency and wavelength-frequency dispersion
curves with modelled shear modulus-depth profile. Data from a CSWS survey
using a 70-kg weight ground vibrator with 489 N force (see Figure 11.5).
Offset (m)
20
40
60
80
100
B
A
G
(a)
(b)
Energy(%)
020406080100
Dispersion image
E
D
E
1400
E
1200
1000
800
600
400
200
B
C1
F
C1
A
C
C0
F
10
20
30
40
50
60
70
80
90
100
Frequency (Hz)
F
Figure 14.4
(a) MASW seismic data obtained using active and passive
sources. (b) Wavefield transformation into a dispersion image that separates
out the Rayleigh wave fundamental (C0) from its higher harmonics (C1), an
air wave (A) and reflections and refractions (E and B). A dispersion curve
is manually or automatically picked by tracing the peak of C0 (and higher
harmonic modes if required). Reproduced with kind permission of C. Park,
Kansas Geological Survey.
